IMPROVEMENT TO OZONATING WATER FOR POST-HARVEST WASHING THROUGH NANOBUBBLES

Abstract. As consumer demand for fresh produce continues to grow, so do concerns by the Food and Drug Administration (FDA) about foodborne illnesses and foodborne disease outbreaks. Postharvest wash is a critical control point in fresh produce processing for reducing or eliminating pathogens and other field-acquired contaminants that can result in such outbreaks. Current methods of post-harvest washing typically rely on peracetic acid or chlorine-based sanitizers, which provide less than 100% efficacy in removing pathogens and are generally acknowledged to have negative environmental and worker safety impacts. Due to such concerns, certain European countries have banned the use of chlorine as a sanitizing technique for fresh produce. One alternative sanitizing agent being adopted with greater frequency is ozone gas. Ozone, in both its gaseous and aqueous phases, is generally recognized as safe by the FDA and has been shown to effectively reduce microbial contamination; however, worker safety and environmental concerns still exist when ozone is not properly managed. Additionally, ozone’s poor solubility, limited resident time in solution, and the high cost of ozone generators have contributed to its limited adoption by the agriculture industry. En Solución has developed a novel method for utilizing nano-sized bubbles of ozone gas at the point of postharvest wash. Unlike traditional macro-sized bubbles from existing technologies, the nanobubbles produced by the En Solución methodology have the remarkable ability to remain stable and in solution in high concentrations for orders of magnitude longer in duration than traditional bubbles and dissolved gas. Worker safety is greatly improved as the ozone does not outgas to the environment, but rather, reverts back to oxygen while in the solution. This keeps more ozone in aqueous form and out of the worker environment with additional benefit of greatly enhancing total system efficiency. The technology developed by En Solución also has implications on water management, as the method reduces the amount of fresh makeup water required in washing and facilitates downstream reuses of the water since ozone does not result in any harmful byproducts. During the Phase I project, En Solución developed and validated its technology for application in postharvest washing in consultation with experts in food safety, nanotechnology, applied science, agricultural workplace, health and safety, and sustainable agriculture practices. In Phase II, En Solución will undertake rigorous field testing of its technology in a series of pilot studies conducted at four separate laboratory and commercial fresh-cut vegetable processing facilities. By design, these studies will increase in complexity and operational fidelity to culminate in the installation of En Solución technology at a large commercial operation with product bound for consumers. These real-world demonstrations will provide external validation of En Solución’s technology as a microbial solution and determine the degree to which the technology presents an improvement over existing sanitizers in terms of safety to workers and the environment, cost, impact on the product, and consumer acceptability.Project Narrative. Existing postharvest wash processes for fresh produce provide less than 100% efficacy in eliminating pathogens that result in foodborne illnesses and are generally acknowledged to have negative environmental and worker safety impacts. En Solución’s novel method of automated ozone nanobubble generation provides a chemical-free postharvest sanitizing method that increases efficacy in pathogen reduction while addressing shortcomings of the current methods.